MFC入门示例之单选框、复选框

设置默认选中一个单选按钮，OnInitDialog()函数中添加:

CheckRadioButton(IDC_RADIO1, IDC_RADIO2, IDC_RADIO2);

按钮事件处理

void CMFCApplication3Dlg::OnBnClickedChkBlue()
{
    // 选中蓝色让对话框失效，触发清除背景
    Invalidate();
}

void CMFCApplication3Dlg::OnBnClickedChkRed()
{
    OnBnClickedChkBlue();
}

void CMFCApplication3Dlg::OnBnClickedChkGreen()
{
    OnBnClickedChkBlue();
}

void CMFCApplication3Dlg::OnBnClickedRadio1()
{
    OnBnClickedChkBlue();
}

//清除背景时画图
BOOL CMFCApplication3Dlg::OnEraseBkgnd(CDC* pDC)
{
    // TODO: 在此添加消息处理程序代码和/或调用默认值
    BOOL bRet = CDialogEx::OnEraseBkgnd(pDC);
    int nRed, nGreen, nBlue;
    nRed = m_chk_red.GetCheck() ? 255 : 0;
    nGreen = m_chk_green.GetCheck() ? 255 : 0;
    nBlue = m_chk_blue.GetCheck() ? 255 : 0;

    COLORREF crFore = RGB(nRed, nGreen, nBlue);
    CBrush brush;
    brush.CreateSolidBrush(crFore);
    CBrush *pOldBrush = pDC->SelectObject(&brush);

    RECT rc = { 50,20,150,120 };
    if (m_rd_rect.GetCheck()) {
        pDC->Rectangle(&rc);
    }
    else {
        pDC->Ellipse(&rc);
    }
    pDC->SelectObject(pOldBrush);

    return bRet;
}